Carburetor



0 M 9, N. m 1 K 5 H Q a .u C 2 fin C. H. KIRBY CARBURETOR Filed Oct. 5, 1927 ii! I I July 25, 1933.

Patented July 25, 1933 UNITED STATES PATENT OFFlCE CHARLES H. KIRBY, OF FLINT, MICHIGAN, ASSIGNOR TO MARVEL CABBURETER COM- PANY, OF FLINT, MICHIGAN, A CORPORATION OF ILLINOIS CARBUREIOR Application filed October 5, 1927. Serial 1 10. 224,035.

This invention relates to a carburetor for use with internal combustion engines, and more particularly to a choke mixture control for carburetors of this class.

In general, most carburetors are provided with a choke valve for temporarily cutting off or limiting the supply of air to the carburetor at the time of starting the motor, but no provision is made for admitting the fuel mixture to the intake manifold of the engine if the throttle valve happens to be closed or substantially closed at the time the choke valve is used. The result is that an insuflicient supply of fuel mixture is made available for the engine and the engine fails to start as sures in the specification and the accompanyin drawing.

6n the drawing:

Figure 1 is a side elevational view of a carburetor provided with a choke mixture control embodying the principles of my invention.

Figure 2 is a fragmentary sectional view taken on line IIII of Figure 1.

Figure 3 is a fragmentary view taken online IIIIII of Figure 1.

The reference numeral 1 indicates as a whole a carburetor for use with internal combustion engines. It will be understood that no particular type or design of carburetor is intended, since the choke mixture control of my invention is applicable to practically any type of carburetor. Said carburetor 1 comprises a casing forming an interior mixing chamber 2 having an air intake 3 and a fuel intake 4 leading thereinto. Said mixing chamber 2 is further provided with an upper outlet port 5 communicating with the intake manifold by a pipe 6. A throttle-valve 7 of the usual butterfly type is disposed within the 50 outlet port 5, substantially closing the same" when in closed position. A choke valve'8 is positioned within the air intake port 3 for controlling the air supply to the mixing chamber 2. Said choke valve 8, as usual, is supported upon an axis '9 extending through the walls of the air intake 3 and journalled therein. A lever is secured to one extended end of said axis 9 and is in turn connected by suitable wire or cable (not shown) at its free end 11. It will thus be apparent that swinging movement of the lever 10 will effect corresponding movement of the choke valve 8 to open or close the same.

The primary fuel supply at low or idling speeds is through a nozzle discharging at the throat of a low speed venturi 26 formed in a table 27' interposed between the axis of an air valve 28 and the wall of the chamber-2, the air valve being substantially closed during idling operation so that whatever air passes the closed choke valve passes through the low speed venturi 26. The air valve 28 is.

hinged at 29 adjacent the table 27 and its opening movement is opposed by an adjustable dashpot within which a piston is reciprocated by a connecting rod 31.

In accordance with the principles of my invention, a passage 12 of relatively small bore is'provided in one wall of the carburetor casing to form a by-pass between the mixing chamber 2 and the outer end of the discharge port 5 beyond the throttle valve 7. A transverse passage 13, closed at itsouter end by plug 14, completes this communication. In the lower end of the passage 12 immediately above the low speed Venturi outlet or table 27, there is formed an enlarged valve seat 15 for receiving a rotary type hollow plug valve 16 having an opening 17 adapted to register with said passage 12. The outer end 18 of said plug valve 16 projects outwardly from a boss 19 formed in said casing wall, and is secured to a lever 20. A link 21 is pivotally connected at 22 to one .end of said lever 20 and is pivotally connected as at 23 to an in termediate portion of the lever 10, whereby upon closing of the choke valve 8, the rotary valve 16 is turned to open the by-pass communication 12 between the mixing chamber 2 and the discharge port 5 beyond the throttle valve 7. A strip 24 of resilient metal serves to hold the plug valve 16 in position.

It will thus be apparent that should the throttle valve 7 be allowed to remain closed, as in starting the motor, the action of closing the choke valve 8 will result in the opening of the passage 12 through the aperture 17 in the hollow valve 16, so that the fuel mixture will be allowed to pass from the mixing chamber 2 around the throttle valve 7 into the pipe 6 leading to the intake manifold. This automatic choke mixture control prevents cutting ofi"the supply of fuel mixture to the engine to such an extent that the eng'ine Will fail to start.

In the operation of the carburetor at low idling speeds the engine suction is sufficient to draw fuel from the nozzle 25 but the air flow above the vent'uri 26 is insufficient to car ry the Withdrawn fuel up to the throttle, the fuel thus tending to deposit out of the air flow as the latter dissipates its velocity in the enlarged space of the chamber 2 above the table 27. to gather on the table and since the bypass 12 opens adjacent thereto the energetic. air flow, induced through the bypass by the high manifold suction above the throttle, attracts this fuel which is picked up almost as rapidly as it approaches the table 27 and is delivered through the bypass. By so picking up this otherwise unused fuel delivered by the nozzle, such fuel is worked over into a satisfactory idling mixture, and serves to reduce the required period of choking by half, in addition to assuring prompter and more certain starting in cold weather.

It is thus apparent that a carburetor provided with my improved choke mixture control will give better service in the hands of inexperienced drivers than the usual type of carburetor, and will eliminate one of the chief reasons for delayed starting of the motor.

I am aware that many changes may be made, and numerous details of construction This otherwise unused fuel tends may be varied through a wide range without departing from the principles of this invention, and I therefore do not purpose limiting the patent granted hereon, otherwise than necessitated by the prior art.

I claim as my invention:

1. In a carburetor, a casing-forming a fuel mixing chamber having air and fuel inlets thereto and a throttle valve controlled outlet, a choke valve in said air inlet, a bypass mixturepassage leading from said mixing chamber at a point close to the fuel inlet thereto, means adapted to collect precipitated liquid fuel discharged from said fuel inlet and to supply the same to the inlet of thereto and a throttle valve controlled outlet, a choke device for controlling the intake of air from the air inlet, a bypass mixture passage leading from said mixing chamber at a point adjacent the fuel inlet thereto, means adapted to collect precipitated liquid fuel discharged from said fuel inlet and to supply the same to the inlet of said bypass passage, said passage forming a mixture bypass around said throttle and discharging into the mixture chamber outlet above the throttle, and valve means controlling said bypass mixture passage and rendered effective by the closing of said choke device, said bypass passage serving to apply suction adjacent the fuel inlet to pick up fuel mixture adjacent the fuel inlet during choking.

CHARLES H. KIRBY. 

